There exist many types of gas-heated infrared radiant elements in which the combustion of a mixture of combustible gas and air is used to heat a radiant element that radiates infrared radiation.
It is known to use systems of gas-heated radiant elements, consisting of at least one row of radiant elements installed one next to the other in a transversal direction in relation to a passing strip that has to be dried, such as e.g. a strip of paper that has just been coated at least on one side in order to produce coated paper, which strip is moved in front of the radiant elements.
The combustion air tubes and gas tubes, or the tubes for the mixture of combustion air and gas, are traditionally situated at the backside of the radiant elements of which the front side, that is the radiating side, is situated in front of the passing strip.
Traditionally, the fixed pipe to which a radiant element is fastened is a tube of a mixture of combustion air and gas, and this pipe is at the end equipped with a flange perforated with holes in which screws can be inserted.
Each radiant element is fastened in a traditional way by means of screws accessible at the back of the radiant element, the latter being extracted at the front when the drying installation comes to a standstill. The disassembly of a traditional radiant element thus makes it necessary to have access both from the front side and the backside to the system of radiant elements, which might necessitate the presence of two operators, one who unscrews the screws at the back, while the other takes out the radiant element at the front as soon as the screws are removed.
Such a replacement operation of a radiant element therefore is relatively long and expensive.
According to WO 00/79045 there exists an appliance for connecting a gas-heated infrared radiant element to a fixed gas tube connected to a gas tube, in which a combustion air tube is placed between the gas tube and the radiant element that holds on its back casing a back supply tube of a mixture of air and gas adapted to be connected to the fixed pipe and to be in communication with the air tube, and the appliance has detachable connection devices supported respectively, the first, by the back tube and the second, by the fixed pipe, and that are complementary to one another, and these detachable connection devices are arranged so as to be joined to one another or loosened from one another by one single person placed in front of the front side of the radiant element.
This appliance is interesting to the extent that the back tube of the represented radiant element is fastened by means that constitute a quick connect coupling to a support containing the gas tube.
U.S. Pat. No. 5,062,788, on which the preamble of claim 1 is based, describes an appliance for providing air and gas to a gas burner, which gas burner comprises a back tube for receiving air and gas to be combusted. The appliance comprises an air tube and a gas tube which gas tube comprising an aperture for providing gas inwards to the air tube. the air tube comprising a first aperture for receiving the back tubing, which first aperture of the gas tube and the first aperture of the air tube being aligned. The described assembly of air-gas appliance and burners are difficult do disassemble and may be difficult to work in modules. In order to maintain or repair defect elements of the burners, the whole appliance is to be disassembled which is extremely time consuming.